| // SPDX-License-Identifier: GPL-2.0 |
| |
| /* |
| * IPMB driver to receive a request and send a response |
| * |
| * Copyright (C) 2019 Mellanox Techologies, Ltd. |
| * |
| * This was inspired by Brendan Higgins' ipmi-bmc-bt-i2c driver. |
| */ |
| |
| #include <linux/acpi.h> |
| #include <linux/errno.h> |
| #include <linux/i2c.h> |
| #include <linux/miscdevice.h> |
| #include <linux/module.h> |
| #include <linux/mutex.h> |
| #include <linux/poll.h> |
| #include <linux/slab.h> |
| #include <linux/spinlock.h> |
| #include <linux/wait.h> |
| |
| #define MAX_MSG_LEN 128 |
| #define IPMB_REQUEST_LEN_MIN 7 |
| #define NETFN_RSP_BIT_MASK 0x4 |
| #define REQUEST_QUEUE_MAX_LEN 256 |
| |
| #define IPMB_MSG_LEN_IDX 0 |
| #define RQ_SA_8BIT_IDX 1 |
| #define NETFN_LUN_IDX 2 |
| |
| #define GET_7BIT_ADDR(addr_8bit) (addr_8bit >> 1) |
| #define GET_8BIT_ADDR(addr_7bit) ((addr_7bit << 1) & 0xff) |
| |
| #define IPMB_MSG_PAYLOAD_LEN_MAX (MAX_MSG_LEN - IPMB_REQUEST_LEN_MIN - 1) |
| |
| #define SMBUS_MSG_HEADER_LENGTH 2 |
| #define SMBUS_MSG_IDX_OFFSET (SMBUS_MSG_HEADER_LENGTH + 1) |
| |
| struct ipmb_msg { |
| u8 len; |
| u8 rs_sa; |
| u8 netfn_rs_lun; |
| u8 checksum1; |
| u8 rq_sa; |
| u8 rq_seq_rq_lun; |
| u8 cmd; |
| u8 payload[IPMB_MSG_PAYLOAD_LEN_MAX]; |
| /* checksum2 is included in payload */ |
| } __packed; |
| |
| struct ipmb_request_elem { |
| struct list_head list; |
| struct ipmb_msg request; |
| }; |
| |
| struct ipmb_dev { |
| struct i2c_client *client; |
| struct miscdevice miscdev; |
| struct ipmb_msg request; |
| struct list_head request_queue; |
| atomic_t request_queue_len; |
| size_t msg_idx; |
| spinlock_t lock; |
| wait_queue_head_t wait_queue; |
| struct mutex file_mutex; |
| }; |
| |
| static inline struct ipmb_dev *to_ipmb_dev(struct file *file) |
| { |
| return container_of(file->private_data, struct ipmb_dev, miscdev); |
| } |
| |
| static ssize_t ipmb_read(struct file *file, char __user *buf, size_t count, |
| loff_t *ppos) |
| { |
| struct ipmb_dev *ipmb_dev = to_ipmb_dev(file); |
| struct ipmb_request_elem *queue_elem; |
| struct ipmb_msg msg; |
| ssize_t ret = 0; |
| |
| memset(&msg, 0, sizeof(msg)); |
| |
| spin_lock_irq(&ipmb_dev->lock); |
| |
| while (list_empty(&ipmb_dev->request_queue)) { |
| spin_unlock_irq(&ipmb_dev->lock); |
| |
| if (file->f_flags & O_NONBLOCK) |
| return -EAGAIN; |
| |
| ret = wait_event_interruptible(ipmb_dev->wait_queue, |
| !list_empty(&ipmb_dev->request_queue)); |
| if (ret) |
| return ret; |
| |
| spin_lock_irq(&ipmb_dev->lock); |
| } |
| |
| queue_elem = list_first_entry(&ipmb_dev->request_queue, |
| struct ipmb_request_elem, list); |
| memcpy(&msg, &queue_elem->request, sizeof(msg)); |
| list_del(&queue_elem->list); |
| kfree(queue_elem); |
| atomic_dec(&ipmb_dev->request_queue_len); |
| |
| spin_unlock_irq(&ipmb_dev->lock); |
| |
| count = min_t(size_t, count, msg.len + 1); |
| if (copy_to_user(buf, &msg, count)) |
| ret = -EFAULT; |
| |
| return ret < 0 ? ret : count; |
| } |
| |
| static ssize_t ipmb_write(struct file *file, const char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| struct ipmb_dev *ipmb_dev = to_ipmb_dev(file); |
| u8 rq_sa, netf_rq_lun, msg_len; |
| union i2c_smbus_data data; |
| u8 msg[MAX_MSG_LEN]; |
| ssize_t ret; |
| |
| if (count > sizeof(msg)) |
| return -EINVAL; |
| |
| if (copy_from_user(&msg, buf, count)) |
| return -EFAULT; |
| |
| if (count < msg[0]) |
| return -EINVAL; |
| |
| rq_sa = GET_7BIT_ADDR(msg[RQ_SA_8BIT_IDX]); |
| netf_rq_lun = msg[NETFN_LUN_IDX]; |
| |
| if (!(netf_rq_lun & NETFN_RSP_BIT_MASK)) |
| return -EINVAL; |
| |
| /* |
| * subtract rq_sa and netf_rq_lun from the length of the msg passed to |
| * i2c_smbus_xfer |
| */ |
| msg_len = msg[IPMB_MSG_LEN_IDX] - SMBUS_MSG_HEADER_LENGTH; |
| if (msg_len > I2C_SMBUS_BLOCK_MAX) |
| msg_len = I2C_SMBUS_BLOCK_MAX; |
| |
| data.block[0] = msg_len; |
| memcpy(&data.block[1], msg + SMBUS_MSG_IDX_OFFSET, msg_len); |
| ret = i2c_smbus_xfer(ipmb_dev->client->adapter, rq_sa, |
| ipmb_dev->client->flags, |
| I2C_SMBUS_WRITE, netf_rq_lun, |
| I2C_SMBUS_BLOCK_DATA, &data); |
| |
| return ret ? : count; |
| } |
| |
| static unsigned int ipmb_poll(struct file *file, poll_table *wait) |
| { |
| struct ipmb_dev *ipmb_dev = to_ipmb_dev(file); |
| unsigned int mask = POLLOUT; |
| |
| mutex_lock(&ipmb_dev->file_mutex); |
| poll_wait(file, &ipmb_dev->wait_queue, wait); |
| |
| if (atomic_read(&ipmb_dev->request_queue_len)) |
| mask |= POLLIN; |
| mutex_unlock(&ipmb_dev->file_mutex); |
| |
| return mask; |
| } |
| |
| static const struct file_operations ipmb_fops = { |
| .owner = THIS_MODULE, |
| .read = ipmb_read, |
| .write = ipmb_write, |
| .poll = ipmb_poll, |
| }; |
| |
| /* Called with ipmb_dev->lock held. */ |
| static void ipmb_handle_request(struct ipmb_dev *ipmb_dev) |
| { |
| struct ipmb_request_elem *queue_elem; |
| |
| if (atomic_read(&ipmb_dev->request_queue_len) >= |
| REQUEST_QUEUE_MAX_LEN) |
| return; |
| |
| queue_elem = kmalloc(sizeof(*queue_elem), GFP_ATOMIC); |
| if (!queue_elem) |
| return; |
| |
| memcpy(&queue_elem->request, &ipmb_dev->request, |
| sizeof(struct ipmb_msg)); |
| list_add(&queue_elem->list, &ipmb_dev->request_queue); |
| atomic_inc(&ipmb_dev->request_queue_len); |
| wake_up_all(&ipmb_dev->wait_queue); |
| } |
| |
| static u8 ipmb_verify_checksum1(struct ipmb_dev *ipmb_dev, u8 rs_sa) |
| { |
| /* The 8 lsb of the sum is 0 when the checksum is valid */ |
| return (rs_sa + ipmb_dev->request.netfn_rs_lun + |
| ipmb_dev->request.checksum1); |
| } |
| |
| static bool is_ipmb_request(struct ipmb_dev *ipmb_dev, u8 rs_sa) |
| { |
| if (ipmb_dev->msg_idx >= IPMB_REQUEST_LEN_MIN) { |
| if (ipmb_verify_checksum1(ipmb_dev, rs_sa)) |
| return false; |
| |
| /* |
| * Check whether this is an IPMB request or |
| * response. |
| * The 6 MSB of netfn_rs_lun are dedicated to the netfn |
| * while the remaining bits are dedicated to the lun. |
| * If the LSB of the netfn is cleared, it is associated |
| * with an IPMB request. |
| * If the LSB of the netfn is set, it is associated with |
| * an IPMB response. |
| */ |
| if (!(ipmb_dev->request.netfn_rs_lun & NETFN_RSP_BIT_MASK)) |
| return true; |
| } |
| return false; |
| } |
| |
| /* |
| * The IPMB protocol only supports I2C Writes so there is no need |
| * to support I2C_SLAVE_READ* events. |
| * This i2c callback function only monitors IPMB request messages |
| * and adds them in a queue, so that they can be handled by |
| * receive_ipmb_request. |
| */ |
| static int ipmb_slave_cb(struct i2c_client *client, |
| enum i2c_slave_event event, u8 *val) |
| { |
| struct ipmb_dev *ipmb_dev = i2c_get_clientdata(client); |
| u8 *buf = (u8 *)&ipmb_dev->request; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&ipmb_dev->lock, flags); |
| switch (event) { |
| case I2C_SLAVE_WRITE_REQUESTED: |
| memset(&ipmb_dev->request, 0, sizeof(ipmb_dev->request)); |
| ipmb_dev->msg_idx = 0; |
| |
| /* |
| * At index 0, ipmb_msg stores the length of msg, |
| * skip it for now. |
| * The len will be populated once the whole |
| * buf is populated. |
| * |
| * The I2C bus driver's responsibility is to pass the |
| * data bytes to the backend driver; it does not |
| * forward the i2c slave address. |
| * Since the first byte in the IPMB message is the |
| * address of the responder, it is the responsibility |
| * of the IPMB driver to format the message properly. |
| * So this driver prepends the address of the responder |
| * to the received i2c data before the request message |
| * is handled in userland. |
| */ |
| buf[++ipmb_dev->msg_idx] = GET_8BIT_ADDR(client->addr); |
| break; |
| |
| case I2C_SLAVE_WRITE_RECEIVED: |
| if (ipmb_dev->msg_idx >= sizeof(struct ipmb_msg)) |
| break; |
| |
| buf[++ipmb_dev->msg_idx] = *val; |
| break; |
| |
| case I2C_SLAVE_STOP: |
| ipmb_dev->request.len = ipmb_dev->msg_idx; |
| |
| if (is_ipmb_request(ipmb_dev, GET_8BIT_ADDR(client->addr))) |
| ipmb_handle_request(ipmb_dev); |
| break; |
| |
| default: |
| break; |
| } |
| spin_unlock_irqrestore(&ipmb_dev->lock, flags); |
| |
| return 0; |
| } |
| |
| static int ipmb_probe(struct i2c_client *client, |
| const struct i2c_device_id *id) |
| { |
| struct ipmb_dev *ipmb_dev; |
| int ret; |
| |
| ipmb_dev = devm_kzalloc(&client->dev, sizeof(*ipmb_dev), |
| GFP_KERNEL); |
| if (!ipmb_dev) |
| return -ENOMEM; |
| |
| spin_lock_init(&ipmb_dev->lock); |
| init_waitqueue_head(&ipmb_dev->wait_queue); |
| atomic_set(&ipmb_dev->request_queue_len, 0); |
| INIT_LIST_HEAD(&ipmb_dev->request_queue); |
| |
| mutex_init(&ipmb_dev->file_mutex); |
| |
| ipmb_dev->miscdev.minor = MISC_DYNAMIC_MINOR; |
| |
| ipmb_dev->miscdev.name = devm_kasprintf(&client->dev, GFP_KERNEL, |
| "%s%d", "ipmb-", |
| client->adapter->nr); |
| ipmb_dev->miscdev.fops = &ipmb_fops; |
| ipmb_dev->miscdev.parent = &client->dev; |
| ret = misc_register(&ipmb_dev->miscdev); |
| if (ret) |
| return ret; |
| |
| ipmb_dev->client = client; |
| i2c_set_clientdata(client, ipmb_dev); |
| ret = i2c_slave_register(client, ipmb_slave_cb); |
| if (ret) { |
| misc_deregister(&ipmb_dev->miscdev); |
| return ret; |
| } |
| |
| return 0; |
| } |
| |
| static int ipmb_remove(struct i2c_client *client) |
| { |
| struct ipmb_dev *ipmb_dev = i2c_get_clientdata(client); |
| |
| i2c_slave_unregister(client); |
| misc_deregister(&ipmb_dev->miscdev); |
| |
| return 0; |
| } |
| |
| static const struct i2c_device_id ipmb_id[] = { |
| { "ipmb-dev", 0 }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(i2c, ipmb_id); |
| |
| static const struct acpi_device_id acpi_ipmb_id[] = { |
| { "IPMB0001", 0 }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(acpi, acpi_ipmb_id); |
| |
| static struct i2c_driver ipmb_driver = { |
| .driver = { |
| .name = "ipmb-dev", |
| .acpi_match_table = ACPI_PTR(acpi_ipmb_id), |
| }, |
| .probe = ipmb_probe, |
| .remove = ipmb_remove, |
| .id_table = ipmb_id, |
| }; |
| module_i2c_driver(ipmb_driver); |
| |
| MODULE_AUTHOR("Mellanox Technologies"); |
| MODULE_DESCRIPTION("IPMB driver"); |
| MODULE_LICENSE("GPL v2"); |